1. Field of the Invention
This invention relates to a device that uses a fluid to dampen a force that tends to move the plane of rotation of a steerable wheel or wheels of a vehicle having a shaft used to steer such wheel or wheels away from being generally parallel to the frame of such vehicle. It also relates to any steering device, such as a ski of a snowmobile or the exhaust jet of a personal watercraft, that uses a shaft or the like in the steering process.
2. Description of the Related Art
U.S. Pat. No. 4,773,514 for a Hydraulic Damping Device is quite similar to the present invention.
A wing 23 is rotatably mounted within a hollow chamber 11 of a casing 6. Either the wing 23 or the casing 6 is rigidly attached to a portion of a motorcycle that rotates with the fork that holds the front wheel of a motorcycle. The other of these two elements, i.e., either the casing 6 or the wing 23 is rigidly connected to the frame of the motorcycle. Therefore, whenever the front wheel of the motorcycle is turned to the left or right, there will be relative motion between the wing 23 and the casing 6.
The chamber 11 is sealed to prevent the leakage of a fluid and is filled with hydraulic fluid. The wing 23 is xe2x80x9cdimensioned to fit sealingly to the bottom part 12, the cover 13 and the inside of the peripheral wall 10cxe2x80x9d so that hydraulic fluid cannot pass around the wing 23. Movement of the wing 23 is, consequently, impeded by the hydraulic fluid, thereby dampening the turning left and right of the front wheel.
The degree of dampening is controlled with a channel 24 in the cover 13 for the casing 6. The channel 24 has ports near the sides 10a, 10b of the chamber 11 which permit hydraulic fluid to flow around the wing 23. The effective cross-sectional area of channel 24 is controlled by a screw 27 that by being turned is inserted farther into channel 24. The farther screw 27 is inserted into channel 24, the smaller is the effective area of channel 24 and the greater is the impedance to the flow of hydraulic fluid and, therefore, the dampening.
As the knob 29 which turns the screw 27 is moved radially, a spring-loaded ball 33 fits into a number of circumferentially distributed bores 32 having a smaller diameter than the ball 33 to xe2x80x9cfacilitate proper settingxe2x80x9d of the screw 27. Still, it is difficult precisely to determine the degree to which the screw 27 has intruded within the channel 24 and, therefore, the degree of dampening that will be achieved.
Moreover, a somewhat complex system employing two valve balls 34, 35 and a pressure spring 42 which maintains the balls 34, 35 in their open positions until the flow of hydraulic fluid, caused by a rapid turning of the front wheel, forces one or the other of the balls 34, 35, depending upon the direction of the turn, closed. Unfortunately, contaminants, such as those created through the wear of parts in the Hydraulic Damping Device, can cause such a valving system to stick.
Additionally, bypass channels 25 and 26 eliminate dampening near the center of chamber 11 by allowing hydraulic fluid to flow from the center to the sides of chamber 11. The extent of the central area where dampening has been eliminated is determined by rotating a sleeve to align one of several different openings 56a, b, c, d and 57a, b, c, d with one of several different connecting ports 47a, b, c, d and 48a, b, c, d. 
Having all ports for the bypass channels in the cover 13, however creates the possibility that when the wing 23 is near either side 10a or side 10b, the wing will either be farther toward such side 10a or 10b than is any port or will be under the port closest to such side 10a or 10b. Because the wing 23 is xe2x80x9cdimensioned to fit sealingly to the bottom part 12, the cover 13 and the inside of the peripheral wall 10cxe2x80x9d so that hydraulic fluid cannot pass around the wing 23, either of these possible situations will preclude hydraulic fluid from being transferred to the side of the wing 23 that is toward the nearer side 10a, 10b and thereby impede the proper functioning of the wing 23.
The angular size of chamber 11 is not specified. From FIG. 2, however, it appears to be substantially less than 180 degrees.
Ours can move through a full 180 degrees.
The basic features of the present Fluidic Dampening Device are similar to those of U.S. Pat. No. 4,773,514, i.e., a housing contains a generally sector-shaped chamber having a first side wall, a second side wall, a peripheral wall, a bottom, and a rotatably mounted wiper. A faceplate is sealingly mounted to the top of the housing. And the wiper has dimensions such that it sealingly moves past the faceplate, the bottom of the housing, and the periphal wall of the housing.
There is, however, only a single bypass channel; and it is contained within the housing, rather than in the faceplate. Moreover, the bypass channel is kept as simple as possible by containing no valving. This eliminates the possibility of a contaminant causing such a valve to stick.
The bypass channel has a first port in the first side wall, preferably near the peripheral wall, and a second port in the second side wall, preferably near the peripheral wall. Near the first port, the first side wall may contain an extension that is made simply to accommodate the tool that create the chamber in the housing if this is done by grinding or drilling; similarly, near the second port, the second side wall may contain an extension that is made simply to accommodate the tool that create the chamber in the housing if this is done by grinding or drilling.
Having the ports in the side walls eliminates the possibility that the wiper can be so close to a side wall that no fluid can be transferred to the side of the wiper that is nearer to that side wall.
And the amount of dampening is controlled by having indentations of varying sizes formed at distinct points around a control shaft situated so that either no indentation or only one indentation lies within the bypass channel at a given time. Moreover, each indentation in the shaft is aligned with a dxc3xa9tente in the bottom side of a knob attached to the top of the shaft. A spring is placed in a vertical corridor in the housing, which vertical corridor is closed at the bottom. A ball is placed atop the spring so that it presses against the bottom of the knob. The size of each dxc3xa9tente is sufficiently large that the ball entering a detente is very perceptible to one turning the knob. Also, a unique visual indicator, preferably a numeral, is placed above each dxc3xa9tente. Therefore, a user knows precisely the size of the indentation that is in the bypass channel and, therefore, the degree of dampening that will occur.
If the knob is stopped between dxc3xa9tentes, no indentation will be within the bypass channel, i.e., the bypass channel will be completely closed so that dampening is at a maximum.
Grooves are placed in the bottom of the faceplate at desired locations to select areas where there will be no dampening because a viscous fluid, preferably hydraulic fluid, that will be placed in the chamber can flow above the wiper as the wiper turns. This is much simpler than the bypass channels of U.S. Pat. No. 4,773,514 and, consequently, less prone to being clogged by contaminants.
The location of such grooves is selected at the time of manufacture and is, preferably, symmetrical about the center of the chamber and extends to each side wall of the chamber, leaving an area in the center of the chamber where dampening will occur.
Finally, the sector of the chamber in the Hydraulic Damping Device of U.S. Pat. No. 4,773,514 covers only approximately ninety degrees, whereas the sector of the chamber in the present Fluidic Dampening Device is much larger, preferably approximately one hundred twenty degrees.